Numerical-Experimental Comparison in the Simulation of Rotor/Stator Interaction Through Blade-Tip/Abradable Coating Contact

Abstract

Higher aircraft energy efficiency may be achieved by minimizing the clearance between the rotating blade tips and respective surrounding casing. A common technical solution consists in the implementation of an abradable liner which improves both the operational safety and the efficiency of modern turbomachines. However, unexpected abradable wear removal mechanisms were recently observed in experimental set-ups as well as during maintenance procedures. Based on a numerical strategy previously developed, the present study introduces a numerical-experimental comparison of such occurrence.Attention is first paid to the review and analysis of existing experimental results. Good agreement with numerical predictions is then illustrated in terms of critical stress levels within the blade as well as final wear profiles of the abradable liner. Numerical results suggest an alteration of the abradable mechanical properties in order to explain the outbreak of a divergent interaction. New blade designs are also explored in this respect and it is found that the interaction phenomenon is highly sensitive to (1) the blade geometry, (2) the abradable material properties and (3) the distortion of the casing.

Anti-Optimisation Applied to the Analysis of Rotor/Stator Interaction

“…3. This blade design has been used for the simulation of blade/abradable coating interaction in [3]. It was found that it is particularly sensitive to blade/abradable coating interaction around several critical frequencies.…”

“…These simulations are carried out based on the strategy presented in [16], that was applied in [3] and is briefly recalled here for the sake of clarity. For a definition of variables see the Nomenclature at the end of this paper.…”

“…The two dominant alternatives have their own limitations: case-by-case transient analysis [3] can be prohibitively slow for complex systems, and methods for approximating periodic solutions such as the harmonic balance method [4] can suffer problems with convergence and accuracy for non-smooth nonlinearities such as blade / casing contact [5]. In order to account for uncertainties a Monte Carlo based approach is usually employed [6] which substantially increases an already significant computational load.…”

Rotor-Stator Interaction Scenarios for the Centrifugal Compressor of a Helicopter Engine

“…Because they may lead to blade failure [1] and increased vibratory levels which may damage the structure, a significant amount of work has been dedicated to the understanding of these phenomena as well as the development of strategies for avoiding them. The repetability of such experiments as well as the possibility to obtain accurate results from numerical simulations [2] indicate that the interaction phenomenon is possibly robust. It is thus of great interest to assess the severity of this phenomenon for other types of compressor such as centrifugal compressors, also named impellers.…”

A Qualitative Numerical Analysis of Rotor-Casing Interactions in Centrifugal Compressors of Helicopter Engines

“…In this area, recent numerical developments focused on a single blade of axial compressors [2,3]. There is now the need for a general methodology relevant to a large family of structures featuring cyclic symmetry for which such interaction occurrences may arise.…”